This invention concerns a luminous false-wall device to be attached to a panel such as a wall or a ceiling. The invention thus pertains to the technical field of stretched false ceilings and false walls, behind which a light source is placed.
False-wall devices comprising a stretched canvas fixed at the base of a chassis frame, generally rectangular, which is made of an association of profiles forming each one of its sides, are known in the prior art. To this end, the canvas comprises an attachment means fixed along its periphery. For example, as described in patent FR 2,630,476, the canvas may be provided with a peripheral hook-shaped outer edge. Another attachment means consists in clips inserted in the profiles, in which the canvas may be secured by pinching. The stretched canvas may be, for example, a textile material or a synthetic polymer material, such as polyvinyl chloride (PVC). The light source illuminates the canvas, which is translucent so as the light may propagate through the canvas and lighten the room in which the luminous false-wall device is installed.
In particular, in an application of the light box type, the assembly canvas/frame is placed in an external frame provided with lateral sides, a bottom side and lighting means. In the latter case, the chassis is fixed to the external frame and the light emitted by the lighting means passes through the translucent canvas.
Whether a false ceiling, a false wall or a light box, the light intensity on the outer side of the canvas is sometimes insufficient relative to the desired effect. On the one hand, the translucent canvas generally has a transmittance in the order of 50%, meaning that 50% of the light intensity is lost. On the other hand, the source of light may be far away from the canvas, which weakens the intensity of light striking it.
Solutions consist in bringing the light source closer to the canvas, to multiply the number of light sources or to increase their power. However, the implementation of these solutions has drawbacks. Moreover, a minimal safety distance is required between the light sources and the canvas to avoid degrading it. In spite of these solutions, there remains a problem of insufficient light intensity.
On the other hand, the profiles forming the chassis generally have a rectangular cross-section, with an upper side facing the wall or ceiling and a lower side facing the canvas. The canvas covers generally the entire lower side of the profile. Thus, when the stretched canvas is observed, the lower side of the profile is visible by transparency or by the shadow they cast on the canvas, creating an unsightly shaded area on all the perimeter of the chassis.
A known solution, described in patent EP 2,494,121, consists in using profiles with a triangular cross-section, with the tip directed toward the canvas and the two others edges are directed towards the wall or ceiling. In this way, only the tip directed toward the canvas can still be visible and the light may pass along the hypotenuse. This solution improves the lighting of the canvas's perimeter, but still does not allow a homogeneous lighting to be obtained on the whole of the canvas surface. Indeed, the profile itself, even if triangular in shape, still casts a shadow on the canvas, creating a shaded area along the perimeter of canvas, with a lighting intensity lower than the rest of the canvas.